A declared weed is a plant listed under state or territory legislation. The listing creates legal obligations: at minimum, you cannot allow it to spread. Depending on the category and your state, you may also be required to actively control it, report its presence, or prevent movement of material that could spread it.
The term "declared weed" is the general concept. Each state and territory manages weeds under its own legislation and its own vocabulary. What every system shares is a tiered approach: the higher the threat, the stricter the obligation. Understanding where a plant sits in your state's framework tells you what you're required to do.
Weed management is primarily a state and territory responsibility under Australia's constitutional arrangement. The federal government coordinates through programs like the Weeds of National Significance framework, but the legal obligations that apply to landowners come from state law.
This matters practically. A weed that's prohibited in Queensland may be unrestricted across the border. Serrated tussock is a major declared species in NSW and Victoria but has different obligations elsewhere. If you're buying land, moving equipment between properties, or managing weed spread near a state boundary, knowing your specific state's list is not optional.
Most states use a tiered structure. The exact names differ but the underlying logic is consistent.
The most restricted category. If found, you must report it and begin eradication. These are typically weeds either not yet established in the region or assessed as posing an extreme risk. Movement of the plant or any material that could spread it is banned. Queensland calls these "prohibited matter"; NSW groups the highest-threat species as P1 priority weeds.
The plant may be established but must not be allowed to spread beyond your property. Active control is required. You cannot sell, move, or give away the plant or its seeds. Obligations may include notifying your local council or following a specific management plan. Queensland calls these "restricted matter".
Lower-tier listings often require management within specific contexts: near waterways, in sensitive habitats, or within a regional management plan. These operate through regional rather than state-wide obligations. The general biosecurity duty of care still applies across all tiers.
The table below shows the main legislative frameworks. For exact category definitions and which species are listed, check your state's biosecurity or agriculture authority directly. Legislation is updated periodically and online databases reflect current status.
| State / Territory | Legislation | Terms used |
|---|---|---|
| New South Wales | Biosecurity Act 2015 | Priority weeds (P1–P4); general biosecurity obligation |
| Queensland | Biosecurity Act 2014 | Prohibited matter, restricted matter |
| Victoria | Catchment and Land Protection Act 1994 | Regionally prohibited, regionally controlled, regionally restricted weeds |
| Western Australia | Biosecurity and Agriculture Management Act 2007 | Declared plants (categories A–E) |
| South Australia | Landscape South Australia Act 2019 | Declared plants |
| Tasmania | Weed Management Act 1999 | Declared weeds (categories A–D) |
| Northern Territory | Weeds Management Act 2001 | Declared weeds |
| ACT | Pest Plants and Animals Act 2005 | Declared plants |
Verify current status with your state's biosecurity authority. Lists and categories are updated as species are assessed.
"Noxious weed" was the standard term in NSW under the Noxious Weeds Act 1993 and in Victoria under earlier catchment legislation. Both states have since updated their legislation and moved away from the term. It still appears in older management plans, roadside signage, and common speech.
For practical purposes, a "noxious weed" and a "declared weed" refer to the same concept: a plant with legal management obligations. If you're working with documentation that uses "noxious", find the current equivalent category under your state's current legislation to understand what's actually required of you now.
Most Australian states include a "general biosecurity obligation" (GBO) in their biosecurity legislation. This obligation is broader than any specific weed list: you must not cause, or risk causing, a biosecurity impact on another person's land, the environment, or primary industries.
The GBO also applies to equipment and livestock movement. If you're moving vehicles, machinery, or animals through areas with known weed infestations, you have a responsibility to remove attached material before leaving. Weed seed spreads on tyres, boots, clothing, and in hay.
The federal government maintains a list of Weeds of National Significance (WONS): currently 32 species assessed as causing major impact across multiple states. The list includes serrated tussock (Nassella trichotoma), parthenium weed (Parthenium hysterophorus), alligator weed (Alternanthera philoxeroides), willow (Salix spp.), and others.
WONS listing is a federal coordination mechanism, not a separate legal obligation. It indicates that the federal government and states are working together on management, and these species are typically declared in every state where they occur. The obligations that apply to you as a landowner still come from your state's legislation.
Examples on WeedScout: alligator weed, serrated tussock, parthenium weed
When you find or suspect a declared weed:
Herbicide information on WeedScout species pages reflects registered uses. Follow the label. For application near waterways or in sensitive areas, verify permit requirements with the APVMA (Australian Pesticides and Veterinary Medicines Authority) or your state authority.
For a prohibited-matter weed, contact your state's biosecurity authority before acting. Some species have specific handling requirements and eradication is often done in coordination with biosecurity officers.
A plant listed under state or territory biosecurity legislation that poses a risk to agriculture, the environment, or human health. The listing creates a legal obligation to manage it: at minimum, you cannot allow it to spread from your land.
"Noxious weed" is the older term from NSW and Victorian legislation. Most states have updated their laws, but the term still appears in older documents. The concept is the same: plants with legal management obligations. Check current legislation for the exact category that applies now.
Penalties depend on your state and the weed's category. For prohibited-category weeds, penalties can be substantial. For lower categories, councils typically issue compliance notices and work with landowners toward control. The general biosecurity obligation means allowing known weed spread carries risk regardless of specific category.
A federal priority list of species causing major impact across multiple Australian states. WONS listing is a coordination framework, not a direct legal obligation for landowners. The obligations you face come from your state's legislation, but WONS species are typically declared in all states where they occur.
Yes, significantly. Each state maintains its own list under its own legislation. A plant prohibited in Queensland may carry no specific obligation across the border. Always check your state's current biosecurity authority for the lists that apply to your land.
Typically not for restricted or prohibited categories. Selling, moving, or giving away declared weed material — including seeds, cuttings, or soil containing propagules — is prohibited under most state biosecurity acts. This includes potted plants, hay, and grain. Check your state's specific requirements.
WeedScout shows declared status for your state alongside field identification cues and control guidance. Works offline, no reception needed.
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